4-3
Each subchannel in the COFDM implementation is about 300 KHz wide. At the low
end of the speed gradient, BPSK (binary phase shift keying) is used to encode 125
Kbps of data per channel, resulting in a 6,000-Kbps, or 6 Mbps, data rate. Using
quadrature phase shift keying, you can double the amount of data encoded to 250
Kbps per channel, yielding a 12-Mbps data rate. And by using 16-level quadrature
amplitude modulation encoding 4 bits per hertz, you can achieve a data rate of
24 Mbps. The 802.11a/g standard specifies that all 802.11a/g-compliant products
must support these basic data rates. The standard also lets the vendor extend the
modulation scheme beyond 24 Mbps. Remember, the more bits per cycle (hertz)
that are encoded, the more susceptible the signal will be to interference and
fading, and ultimately, the shorter the range, unless power output is increased.
Default Key
This option allows you to select the default WEP key. This option allows
you to use WEP keys without having to remember or write them down. The
WEP keys generated using the Pass Phrase is compatible with other WLAN
products. The Pass Phrase option is not as secure as manual assignment.
Device Name
Also known as DHCP client ID or network name. Sometimes provided by an
ISP when using DHCP to assign addresses.
DHCP (Dynamic Host Configuration Protocol)
This protocol allows a computer (or many computers on your network) to be
automatically assigned a single IP address from a DHCP server.
DNS Server Address (Domain Name System)
DNS allows Internet host computers to have a domain name and one or more IP
addresses. A DNS server keeps a database of host computers and their respective
domain names and IP addresses, so that when a user enters a domain name into
the Internet browser, the user is sent to the proper IP address. The DNS server
address used by the computers on your home network is the location of the DNS
server your ISP has assigned.
DSL Modem (Digital Subscriber Line)
A DSL modem uses your existing phone lines to transmit data at high speeds.
Direct-Sequence Spread Spectrum (for 802.11b)
Spread spectrum (broadband) uses a narrowband signal to spread the
transmission over a segment of the radio frequency band or spectrum. Direct-
sequence is a spread spectrum technique where the transmitted signal is spread
over a particular frequency range.
